Medium ejection apparatus to change conveyance speed of ejection roller according to size of medium

ABSTRACT

A medium ejection apparatus includes an ejection roller, an ejection tray to stack a medium ejected by the ejection roller, a drive mechanism to drive the ejection roller, a processor to detect a size of the medium ejected by the ejection roller, and control the drive mechanism to control a conveyance speed of the ejection roller when ejecting the medium. The processor changes the conveyance speed of the ejection roller from a first conveyance speed to a second conveyance speed lower than the first conveyance speed in the middle of ejecting the medium. The processor changes the second conveyance speed in accordance with the size of the medium.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of prior Japanese Patent Application No. 2022-043041, filed on Mar. 17, 2022, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

Embodiments described in the present specification relate to a medium ejection apparatus.

BACKGROUND

A scanner or other medium ejection apparatus conveys a medium while capturing its image and, after capturing its image, ejects the medium to an ejection tray. In such a medium ejection apparatus, conveying several types of a medium having respectively different sizes is being demanded.

Japanese Unexamined Patent Publication No. 6-064815 discloses a sheet post-processing device for ejecting a large sized sheet by a fast speed at which the front end part will not bend due to friction with an ejection tray and a small sized sheet by a slow speed at which it will not fly far off.

SUMMARY

According to some embodiments, a medium ejection apparatus includes an ejection roller, an ejection tray to stack a medium ejected by the ejection roller, a drive mechanism to drive the ejection roller, a processor to detect a size of the medium ejected by the ejection roller, and control the drive mechanism to control a conveyance speed of the ejection roller when ejecting the medium. The processor changes the conveyance speed of the ejection roller from a first conveyance speed to a second conveyance speed lower than the first conveyance speed in the middle of ejecting the medium. The processor changes the second conveyance speed in accordance with the size of the medium.

According to some embodiments, a medium ejection method includes detecting a size of a medium ejected by an ejection roller to eject the medium to an ejection tray, and controlling a drive mechanism to drive the ejection roller, to control a conveyance speed of the ejection roller when ejecting the medium. The conveyance speed of the ejection roller is changed from a first conveyance speed to a second conveyance speed lower than the first conveyance speed in the middle of ejecting the medium. The second conveyance speed is changed in accordance with the size of the medium.

According to some embodiments, a computer-readable, non-transitory medium stores a computer program. The computer program causes a medium ejection apparatus including an ejection roller, an ejection tray to stack a medium ejected by the ejection roller, and a drive mechanism to drive the ejection roller to execute a process including detecting a size of a medium ejected by the ejection roller, and controlling the drive mechanism to control a conveyance speed of the ejection roller when ejecting the medium. The conveyance speed of the ejection roller is changed from a first conveyance speed to a second conveyance speed lower than the first conveyance speed in the middle of ejecting the medium. The second conveyance speed is changed in accordance with the size of the medium.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing a medium ejection apparatus according to an embodiment.

FIG. 2 is a view for explaining a conveyance route inside of a medium ejection apparatus.

FIG. 3 is a block diagram showing the schematic constitution of a medium ejection apparatus.

FIG. 4 is a view showing the schematic constitution of a storage device and processing circuit.

FIG. 5 is a flow chart showing an example of the operation of medium reading processing.

FIG. 6 is a flow chart showing an example of the operation of medium reading processing.

FIG. 7 is a flow chart showing an example of the operation of medium ejection processing.

FIG. 8 is a block diagram showing the schematic constitution of another processing circuit.

DESCRIPTION OF EMBODIMENTS

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory, and are not restrictive of the invention, as claimed.

Hereinafter, a medium ejection apparatus, medium ejection method and control program according to some embodiments will be described with reference to the drawings. However, it should be noted that the technical scope of the invention is not limited to these embodiments, and extends to the inventions described in the claims and their equivalents.

FIG. 1 is a perspective view showing a medium ejection apparatus 100 constituted as an image scanner. The medium ejection apparatus 100 conveys a document as a medium and captures an image of it. The medium is printing paper, thick paper, a card, etc. The medium ejection apparatus 100 may also be a facsimile, copier, multifunction peripheral (MFP), etc. Note that the medium which is conveyed may be something to be printed on, etc., rather than a document and the medium ejection apparatus 100 may also be a printer.

In FIG. 1 , the arrow A1 shows a substantially vertical direction (height direction), the arrow A2 shows a medium conveyance direction, the A3 shows medium ejection direction, and the arrow A4 shows a width direction perpendicular to the medium conveyance direction A2 or the medium ejection direction A3. Below, “upstream” will mean upstream in the medium conveyance direction A2 or medium ejection direction A3, while “downstream” means downstream in the medium conveyance direction A2 or medium ejection direction A3.

The medium ejection apparatus 100 is provided with a first housing 101, second housing 102, stacking tray 103, ejection tray 104, operating device 105, display device 106, etc.

The second housing 102 is located at the inside of the first housing 101 and engages with the first housing 101 to be able to turn by a hinge so as to enable it to be opened and closed at the time of jamming of the medium or the time of cleaning the inside of the medium ejection apparatus 100, etc.

The stacking tray 103 engages with the first housing 101 to be able to stack the conveyed medium. The stacking tray 103 is provided at the side surface of the first housing 101 at the medium supply side to be able to move in the height direction A1. When not conveying the medium, the stacking tray 103 is located at a position at the bottom end so that the medium is easily stacked. When conveying the medium, the stacking tray 103 rises to a position at which the medium stacked at the top most side contacts a later explained pick roller.

The ejection tray 104 is formed on the second housing 102. The ejection tray 104 has a stacking surface 104 a for stacking the medium and stacks the medium ejected from an ejection opening of the first housing 101 and the second housing 102.

The operating device 105 has buttons or other input devices and an interface circuit for acquiring signals from the input devices, receives input operations of a user, and outputs operating signals corresponding to the input operations of a user. The display device 106 has a display including liquid crystals, organic Els (Electro-Luminescence), etc., and an interface circuit for outputting image data to the display and displays the image data on the display. Note that the display device 106 may also be a liquid crystal display with a touch panel function. In that case, the operating device 105 has an interface circuit for acquiring input signals from the touch panel.

FIG. 2 is a view for explaining a conveyance route inside of the medium ejection apparatus 100. The conveyance route inside of the medium ejection apparatus 100 has a first sensor 111, pick roller 112, feed roller 113, separation roller 114, first to fifth conveyance rollers 115 a to 115 e, first to sixth driven rollers 116 a to 116 f, an imaging device 117, ejection roller 118, second sensor 119, third sensor 120, etc.

Note that the numbers of the pick roller 112, feed roller 113, separation roller 114, first to fifth conveyance rollers 115 a to 115 e, first to sixth driven rollers 116 a to 116 f, and/or ejection roller 118 are not limited to single ones and may also be multiple ones. In that case, the plurality of feed rollers 113, separation rollers 114, first to fifth conveyance rollers 115 a to 115 e, first to sixth driven rollers 116 a to 116 f, and/or ejection rollers 118 are located aligned at intervals in the width direction A4.

The surface of the first housing 101 facing the second housing 102 forms a first guide 101 a of the medium conveyance path, while the surface of the second housing 102 facing the first housing 101 forms a second guide 102 a of the medium conveyance path.

The first sensor 111 is located at the stacking tray 103, i.e., at an upstream side of the feed roller 113 and separation roller 114, and detects the stacked state of the medium at the stacking tray 103. The first sensor 111 determines if the stacking tray 103 has the medium stacked on it by a contact detection sensor which generates a predetermined current when the medium contacts it or when the medium does not contact it. The first sensor 111 generates and outputs a first detection signal with a signal value changing between a state where the stacking tray 103 has the medium stacked on it and a state where it does not have it stacked on it. Note that the first sensor 111 is not limited to a contact detection sensor. As the first sensor 111, a photo detection sensor or any other sensor able to detect the presence of a medium may also be used.

The pick roller 112 is provided at the second housing 102. It contacts the medium stacked on the stacking tray 103 when it has risen to substantially the same height as the medium conveyance path and feeds that medium toward the downstream side.

The feed roller 113 is provided inside the second housing 102 at the downstream side from the pick roller 112 and feeds the medium which was stacked at the stacking tray 103 and fed by the pick roller 112 toward the further downstream side. The separation roller 114 is provided inside the first housing 101 facing the feed roller 113. The separation roller 114 is a so-called brake roller or retard roller and is provided to be able to rotate in an opposite direction to the medium conveyance direction or to be able to stop. The feed roller 113 and separation roller 114 perform the operation for separating the medium and separate and feed the medium one sheet at a time. The feed roller 113 is located at the upstream side from the separation roller 114 and the medium ejection apparatus 100 feeds the medium by the so-called top pick method. Note that the feed roller 113 may be located at the downstream side from the separation roller 114 and the medium ejection apparatus 100 may feed the medium by the so-called bottom pick method.

The second sensor 119 is located at the downstream side from the feed roller 113 and separation roller 114 in the medium conveyance direction A1 and at the upstream side from the imaging position of the first imaging device 117 a and the imaging position of the second imaging device 117 b and detects the medium conveyed to that position.

The second sensor 119 includes a light emitter and a light receiver provided at one side (first housing 101) from the medium conveyance path and a light guide tube provided at a position (second housing 102) facing the light emitter and the light receiver across the medium conveyance path. The light emitter is an LED (light emitting diode) etc., and emits light toward the medium conveyance path. On the other hand, the light receiver is a photodiode, etc., and receives light emitted by the light emitter and guided by the light guide tube. When there is the medium present at a position facing the second sensor 119, the light emitted from the light emitter is blocked by the medium, so the light receiver does not detect the light emitted from the light emitter. Based on the intensity of the light received, the light receiver generates and outputs a second detection signal with a signal value changing between the state where there is the medium present at the position of the second sensor 119 and the state where there isn't.

Note that, instead of a light guide tube, a mirror or other reflection member may also be used. Further, the light emitter and the light receiver may also be provided facing each other across the medium conveyance path. Further, the second sensor 119 may detect the presence of the medium by a contact detection sensor which generates a predetermined current when the medium contacts it or when the medium does not contact it, etc. Further, the number of the second sensor 119 is not limited to a single one and may also be multiple ones. In this case, the multiple second sensors 119 are located aligned at intervals in the width direction A4.

The first to fifth conveyance rollers 115 a to 115 e and the first to fifth driven rollers 116 a to 116 e are provided facing each other at the downstream side from the feed roller 113 and separation roller 114. The first to fifth conveyance rollers 115 a to 115 e and the first to fifth driven rollers 116 a to 116 e convey the medium fed by the feed roller 113 and separation roller 114 toward the downstream side.

The imaging devices 117 are located at the downstream side from the first to second conveyance rollers 115 a to 115 b in the medium conveyance direction A2 and capture images of the medium conveyed by the first to second conveyance rollers 115 a to 115 b and first to second driven rollers 116 a to 116 b. The imaging devices 117 include the first imaging device 117 a and the second imaging device 117 b located facing each other across the medium conveyance path.

The first imaging device 117 a has a contact optical system type CIS (contact image sensor) line sensor having imaging elements comprised of CMOS's (complementary metal oxide semiconductors) located in a line in the main scan direction. The first imaging device 117 a has a lens for forming an image on an imaging element and an A/D converter for amplifying the electrical signal output from the imaging element and converting it from an analog to digital (A/D) format. The first imaging device 117 a captures an image of the front surface of the conveyed medium to generate and output an input image.

Similarly, the second imaging device 117 b has a contact optical system type CIS line sensor having imaging elements comprised of CMOS's located in a line in the main scan direction. Further, the second imaging device 117 b has a lens for forming an image on an imaging element and an A/D converter for amplifying the electrical signal output from the imaging element and converting it from an analog to digital (A/D) format. The second imaging device 117 b captures an image of the back surface of the conveyed medium to generate and output an input image.

Note that the medium ejection apparatus 100 may also have only one of the first imaging device 117 a and the second imaging device 117 b located at it and read only one surface of the medium. Further, instead of a contact optical system type CIS line sensor provided with imaging elements comprised of CMOS's, a contact optical system type CIS line sensor provided with imaging elements comprised of CCDs (charge coupled devices) may also be utilized. Further, a reduction optical system type line sensor provided with imaging elements comprised of CMOS's or CCD's may also be utilized.

The third sensor 120 is one example of the medium detection sensor. The third sensor 120 is located at the downstream side from the fifth conveyance roller 115 e and the fifth 5 driven roller 116 e and at the upstream side from the ejection roller 118 and the sixth driven roller 116 f in the medium conveyance direction A1 and detects the medium conveyed to that position. The distance between the third sensor 120 and the ejection roller 118 is preferably set to larger than 2 mm and 5 mm or less in range.

The third sensor 120 includes a light emitter and a light receiver provided at one side from the medium conveyance path (first housing 101) and a light guide tube provided at a position (second housing 102) facing the light emitter and the light receiver across the medium conveyance path. The light emitter is an LED, etc., and emits light toward the medium conveyance path. On the other hand, the light receiver is a photodiode, etc., and receives light emitted by the light emitter and guided by the light guide tube. When there is the medium present at a position facing the third sensor 120, the light emitted from the light emitter is blocked by the medium, so the light receiver does not detect the light emitted from the light emitter. Based on the intensity of the light received, the light receiver generates and outputs a third detection signal with a signal value changing between the state where there is the medium present at the position of the third sensor 120 and the state where there isn't.

Note that, instead of a light guide tube, a mirror or other reflection member may also be used. Further, the light emitter and the light receiver may also be provided facing each other across the medium conveyance path. Further, the third sensor 120 may detect the presence of the medium by a contact detection sensor which generates a predetermined current when the medium contacts it or when the medium does not contact it, etc.

The ejection roller 118 and the sixth driven roller 116 f are provided facing each other at the downstream side from the first to fifth conveyance rollers 115 a to 115 e. The ejection roller 118 and the sixth driven roller 116 f eject the medium conveyed by the first to fifth conveyance rollers 115 a to 115 e and the first to fifth driven rollers 116 a to 116 e to the ejection tray 104. The ejection roller 118 rotates by a drive force transmitted from a drive mechanism 130.

Further, the medium ejection apparatus 100 further has the drive mechanism 130. The drive mechanism 130 drives the ejection roller 118. The drive mechanism 130 includes a first motor 131 and a transmission mechanism 132. The first motor 131 generates a drive force for driving the ejection roller 118 by a control signal from a processing circuit 150. The transmission mechanism 132 includes one or more pulleys, belts, gears, etc., provided between the first motor 131 and the shaft 118 a which is a rotation axis of the ejection roller 118 and transmits the drive force which the first motor 131 generates to the ejection roller 118. The first motor 131 is connected to the ejection roller 118 through the transmission mechanism 132 and drives the ejection roller 118. Due to this, the first motor 131 makes the ejection roller 118 rotate to make the medium be ejected to the ejection tray 104.

Note that the sixth driven roller 116 f may be provided so as to not to rotate driven by the ejection roller 118, but to rotate by the drive force of the first motor 131.

The medium stacked on the stacking tray 103 is conveyed between the first guide 101 a and the second guide 102 a toward the medium conveyance direction A2 by the pick roller 112 and feed roller 113 respectively rotating in the medium feed directions A5, A6. The medium ejection apparatus 100 has as feed modes a separation mode of separating the medium while feeding it and a nonseparation mode of feeding the medium without separating it. The feed mode is set by a user using the operating device 105 or an information processing apparatus connected to communicate with the medium ejection apparatus 100. If the feed mode is set to the separation mode, the separation roller 114 rotates in the direction of the arrow A7, i.e., the opposite direction to the medium feed direction, or stops. Due to this, feed of the medium other than the separated medium is restricted (multi-feed is prevented). On the other hand, if the feed mode is set to the nonseparation mode, the separation roller 114 rotates in the opposite direction of the arrow A7, i.e., the medium feed direction.

The medium is conveyed to the imaging positions of the imaging devices 117 by being guided by the first guide 101 a and the second guide 102 a while the first to second conveyance rollers 115 a to 115 b rotate in the directions of the arrows A8 to A9 and is captured by the imaging devices 117. Furthermore, the medium is ejected onto the ejection tray 104 by the third to the fifth conveyance rollers 115 c to 115 e and ejection roller 118 respectively rotating in the directions of the arrows A10 to A13. The ejection tray 104 stacks the medium ejected by the ejection roller 118.

FIG. 3 is a block diagram showing the schematic constitution of the medium ejection apparatus 100 shown in FIG. 1 . In addition to the above-mentioned constitution, the medium ejection apparatus 100 further has a second motor 133, interface device 134, storage device 140, processing circuit 150, etc.

The second motor 133 includes one or more motors. The second motor 133 makes the pick roller 112, feed roller 113, separation roller 114, and first to fifth conveyance rollers 115 a to 115 e rotate to convey the medium and make the stacking tray 103 move by control signals from the processing circuit 150. The second motor 133 is connected to the rollers and the stacking tray 103 through a not shown transmission mechanism and drives the rollers and the stacking tray 103. Note that the first to fifth driven rollers 116 a to 116 e may be provided to not be ones rotating driven by the first to fifth conveyance rollers 115 a to 115 e, but ones rotating by the drive force of the second motor 133.

Note that the pick roller 112, feed roller 113, separation roller 114, and/or first to fifth conveyance rollers 115 a to 115 e may be provided to not be ones rotating by the drive force from the second motor 133, but ones rotating by the drive force of the first motor 131. In this case, the pick roller 112, feed roller 113, separation roller 114, and/or first to fifth conveyance rollers 115 a to 115 e are provided to be connected with the first motor 131 through the transmission mechanism 132.

The interface device 134 has an interface circuit based on for example a USB (Universal Serial Bus) or other serial bus and is electrically connected with a not shown information processing apparatus (for example, a personal computer, mobile information terminal, etc.,) to transmit and receive input images and various information. Further, instead of the interface device 134, a communication device having an antenna transmitting and receiving wireless signals and a wireless communication interface circuit for transmitting and receiving signals through a wireless communication line in accordance with a predetermined communication protocol may be used. The predetermined communication protocol is for example a wireless LAN (local area network). The communication device may also have a wired communication interface circuit for transmitting and receiving signals through a wired communication line in accordance with a wired LAN or other communication protocol.

The storage device 140 has a RAM (random access memory), ROM (read only memory), or other memory device, hard disk or other fixed disk device, flexible disk, optical disk, or other portable storage device, etc. Further, the storage device 140 stores computer programs, databases, tables, etc., used for various processing of the medium ejection apparatus 100. The computer programs may be installed on the storage device 140 from a computer-readable, non-transitory medium such as a CD-ROM (compact disc read only memory), DVD-ROM (digital versatile disc read only memory), etc., by using a well-known setup program etc.

The processing circuit 150 operates based on programs stored in advance in the storage device 140. The processing circuit is for example a CPU (central processing unit). As the processing circuit 150, a DSP (digital signal processor), LSI (large scale integrated circuit), ASIC (application specific integrated circuit), FPGA (field-programmable gate array), etc., may also be used.

The processing circuit 150 is connected with the operating device 105, display device 106, first sensor 111, imaging devices 117, second sensor 119, third sensor 120, first motor 131, second motor 133, interface device 134, storage device 140, etc., and control these parts. The processing circuit 150 controls the drive by the first motor 131 and second motor 133, controls imaging by the imaging devices 117, etc., based on the first detection signal received from the first sensor 111. The processing circuit 150 acquires input images from the imaging devices 117 and transmits them to the information processing apparatus through the interface device 134.

FIG. 4 is a view showing the schematic constitution of the storage device 140 and the processing circuit 150 shown in FIG. 3 . As shown in FIG. 4 , the storage device 140 stores a control program 141, image acquisition program 142, size detection program 143, and other various programs. These programs are function modules loaded by software operating on a processor. The processing circuit 150 reads the programs stored in the storage device 140 and operates in accordance with the read programs to thereby function as the control module 151, image acquisition module 152, and size detection module 153.

FIG. 5 and FIG. 6 are flow charts showing an example of the operation of the medium reading processing. Below, referring to the flow charts shown in FIG. 5 and FIG. 6 , an example of the operation of the medium reading processing performed at the medium ejection apparatus 100 will be explained. Note that the flow of the operation explained below is mainly performed by the processing circuit 150 in concert with the elements of the medium ejection apparatus 100 based on a program stored in advance in the storage device 140.

First, the control module 151 stands by until receiving an instruction for reading a medium from a user using the operating device 105 or information processing apparatus and receiving an operating signal for instructing reading of the medium is received from the operating device 105 or interface device 134 (step S101).

Next, the control module 151 acquires the first detection signal from the first sensor 111 and determines whether the stacking tray 103 has the medium stacked on it based on the acquired first detection signal (step S102). If the stacking tray 103 does not have the medium stacked on it (No at step S102), the control module 151 returns the processing to step S101 and stands by until newly receiving an operating signal from the operating device 105.

On the other hand, if the stacking tray 103 has the medium stacked on it (Yes at step S102), the control module 151 sets the conveyance speed of the ejection roller 118 to the first conveyance speed (step S103). The conveyance speed of the ejection roller 118 is the speed of movement of the surface of the ejection roller 118 and is the speed by which the medium is conveyed by the ejection roller 118. Similarly, the control module 151 sets the conveyance speed of the feed roller 113 and/or first to fifth conveyance rollers 115 a to 115 e to the first conveyance speed. The control module 151 may also set the conveyance speed of the feed roller 113 to a speed lower than the first conveyance speed.

Next, the control module 151 drives the first motor 131 and the second motor 133 (step S104). The control module 151 controls the second motor 133 to make the stacking tray 103 rise to a position where it can feed the medium. Further, the control module 151 controls the second motor 133 to make the pick roller 112, feed roller 113, separation roller 114, and first to fifth conveyance rollers 115 a to 115 e rotate to make them feed and convey the medium stacked on the stacking tray 103. Further, the control module 151 controls the first motor 131 to make the ejection roller 118 rotate and make it convey the medium fed and conveyed by the feed roller 113, separation roller 114, and first to fifth conveyance rollers 115 a to 115 e. The control module 151 controls the first motor 131 and the second motor 133 so as to make the ejection roller 118, feed roller 113, and first to fifth conveyance rollers 115 a to 115 e rotate at the set conveyance speed.

Next, the control module 151 stands by until the front end of the medium passes the position of the second sensor 119 (step S105). The control module 151 determines whether the front end of the medium has passed the position of the second sensor 119 based on the second detection signal received from the second sensor 119. The control module 151 periodically receives the second detection signal from the second sensor 119 and, if the signal value of the second detection signal changes from a value showing there is no medium present to a value showing there is it present, determines that the front end of the medium has passed the position of the second sensor 119.

If the front end of the medium has passed the position of the second sensor 119 (Yes at step S105), the control module 151 controls the second motor 133 to make the rotation of the pick roller 112, feed roller 113, and separation roller 114 stop and make feed of the medium stop (step S106). The medium fed by the feed roller 113 and separation roller 114 is subsequently conveyed by the first to fifth conveyance rollers 115 a to 115 e and ejection roller 118 and the next medium is not fed.

Next, the image acquisition module 152 stands by until the front end of the medium reaches just before the imaging positions of the imaging devices 117 (step S107). The image acquisition module 152 determines whether the front end of the medium has reached the imaging positions of the imaging devices 117 based on the second detection signal received from the second sensor 119. The image acquisition module 152 periodically receives the second detection signal from the second sensor 119 and, if the signal value of the second detection signal changes from a value showing there is no medium present to a value showing there is it present, determines that the front end of the medium has passed the position of the second sensor 119. The image acquisition module 152 determines that the front end of the medium has reached just before the imaging positions of the imaging devices 117 if the front end of the medium has passed the position of the second sensor 119 or if a first predetermined time period has elapsed from when the front end of the medium has passed the position of the second sensor 119. The first predetermined time period is set to the time required for the medium to move from the position of the second sensor 119 to the imaging positions minus a certain margin. Note that the image acquisition module 152 may also determine whether the front end of the medium has reached just before the imaging positions of the imaging devices 117 by whether a predetermined time period has elapsed from when starting feed of the medium.

If the front end of the medium has reached just before the imaging positions of the imaging devices 117 (Yes at step S107), the image acquisition module 152 makes the imaging devices 117 start capturing images of the medium conveyed (step S108).

Next, the size detection module 153 stands by until the back end of the medium passes the position of the second sensor 119 (step S109). The control module 151 determines whether the back end of the medium has passed the position of the second sensor 119 based on the second detection signal received from the second sensor 119. The control module 151 periodically receives the second detection signal from the second sensor 119 and, if the signal value of the second detection signal changes from a value showing there is the medium present to a value showing there isn't it present, determines that the back end of the medium has passed the position of the second sensor 119.

If the back end of the medium has passed the position of the second sensor 119 (Yes at step S109), the size detection module 153 detects the size of the medium conveyed, i.e., the size of the medium ejected by the ejection roller 118 (step S110). The size detection module 153, for example, detects the size of the medium based on the second detection signal received from the second sensor 119. The size detection module 153 multiplies the time period from when the front end of the medium passes the position of the second sensor 119 to when the back end of the medium passes the position of the second sensor 119 with the conveyance speed of the medium to thereby detect the size of the medium in the medium conveyance direction A2.

The size of the medium detected by the size detection module 153 is utilized in the later explained medium ejection processing for the control module 151 to change the conveyance speed of the ejection roller 118. The larger the size of the medium in the medium conveyance direction A2 is, the greater the force required for ejecting the medium is. By the size detection module 153 detecting the size of the medium in the medium conveyance direction A2, the control module 151 can set the conveyance speed of the ejection roller 118 to a speed suitable for ejection of the medium. Further, the size detection module 153 can utilize the second sensor 119 located at the upstream side from the imaging devices 117 so as to detect the size of the medium early. Therefore, the control module 151 can sufficiently secure the time period until changing the conveyance speed of the ejection roller 118.

Note that several second sensors 119 may be provided and the size detection module 153 may detect the size of the medium in the width direction A4 based on the second detection signals received from the several second sensors 119. In this case, the size detection module 153 periodically receives the second detection signals from the respective several second sensors 119. The size detection module 153 determines that the medium has passed the position of a second sensor 119 sending a second detection signal by whether the signal value of the second detection signal changes from a value showing there is no medium present to a value showing there is it present. The size detection module 153 detects the distance between the two second sensors 119 located at the outer most sides among the second sensors 119 which the medium has passed within a predetermined time period from when the front end of the medium passes the position of any of the second sensors 119 as the size of the medium in the width direction A4. Note that the size detection module 153 may also detect the distance between the two second sensors 119 located at the center most side among the second sensors 119 which the medium has not passed within that predetermined time period as the size of the medium in the width direction A4. The size detection module 153 can detect the size of the medium when the front end of the medium passes the position of a second sensor 119, so can detect the size of the medium earlier and enables the time period until the control module 151 changes the conveyance speed of the ejection roller 118 to be more sufficiently secured.

Further, the size detection module 153 may also multiply the size of the medium in the medium conveyance direction A2 and the size of the medium in the width direction A4 so as to detect the area of the medium as the size of the medium. Due to this, the size detection module 153 can more precisely detect the size of the medium and the control module 151 can set the conveyance speed of the ejection roller 118 to a speed more suitable for ejection of the medium.

Further, the size detection module 153 may also detect the size of the medium based on the input images which the image acquisition module 152 acquires in the later explained processing. In this case, the size detection module 153 calculates the absolute values of the differences in tonal values of adjoining pixels (below, referred to as the “adjoining difference values”) among the pixels in the input images for each of the horizontal direction and vertical direction and, if the adjoining difference value exceeds a tonal threshold value, extracts that pixel as an edge pixel. The tonal value is a brightness value or color value (R value, G value, or B value), etc. The tone threshold value is, for example, set to the difference of the tonal value (for example, 20) enabling a person to be able to visually determine a difference of brightness of the image.

Note that the size detection module 153 may also calculate as the adjoining difference value the absolute value of the difference of tonal values of two pixels separated by exactly a predetermined distance from a pixel inside the input images. Further, the size detection module 153 may also compare the tonal values of the pixels inside the input images with a threshold value to thereby extract the edge pixels. For example, the size detection module 153 detects specific pixels as edge pixels if the tonal values of the specific pixels are less than the threshold value and the tonal values of pixels adjoining the specific pixels or pixels separated from the specific pixels by exactly a predetermined distance are the threshold value or more. The size detection module 153 generates edge images comprised of the edge pixels for each of the horizontal direction and vertical direction.

Next, the size detection module 153 extracts a plurality of lines using Hough transform from the edge images generated for the horizontal direction and vertical direction. Note that the size detection module 153 may also detect lines using the least square method.

Next, the size detection module 153 extracts all combinations of two horizontal direction lines and two vertical direction lines for all of the extracted lines. The size detection module 153 detects as the medium region the rectangular candidate with the largest area among the rectangular candidates configured from the extracted combinations. The size detection module 153 detects the area of the medium region (number of pixels) as the size of the medium. Due to this, the size detection module 153 can more precisely detect the size of the medium and the control module 151 can set the conveyance speed of the ejection roller 118 to a more suitable speed for ejection of the medium.

Next, the image acquisition module 152 stands by until the back end of the medium passes the imaging positions of the imaging devices 117 (step S111). The image acquisition module 152 determines whether the back end of the medium has passed the imaging positions of the imaging devices 117 by whether a second predetermined time period has elapsed from when the back end of the medium passed the position of the second sensor 119. The second predetermined time period is set to the time required for the medium to move from the position of the second sensor 119 to the imaging positions plus a certain margin.

If the back end of the medium has passed the imaging positions of the imaging devices 117 (Yes at step S111), the image acquisition module 152 acquires the input images from the imaging devices 117 and transmits the acquired input images to a not shown information processing apparatus through the interface device 134 (step S112).

Next, the control module 151 determines whether the stacking tray 103 has the medium remaining on it based on the first detection signal received from the first sensor 111 (step S113).

If the stacking tray 103 has the medium remaining on it (Yes at step S113), the control module 151 controls the second motor 133 to make the pick roller 112, feed roller 113, and separation roller 114 rotate to resume feed of the medium (step S114). Next, the control module 151 returns the processing to step S105 and repeats the processing of step S105 and the subsequent processing.

On the other hand, if the stacking tray 103 does not have the medium remaining on it (No at step S113), the control module 151 stands by until the medium currently being conveyed finishes being ejected (step S115). The control module 151 periodically receives a third detection signal from the third sensor 120 and, if the signal value of the third detection signal changes from a value showing there is the medium present to a value showing there isn't, determines that the back end of the medium has passed the position of the third sensor 120. The control module 151 determines whether the medium has finished being ejected by whether a third predetermined time period has elapsed from when the back end of the medium passed the position of the third sensor 120. The third predetermined time period is set to the time required for the medium to move from the position of the second sensor 119 to the position of the ejection roller 118 plus a certain margin. Note that the control module 151 may also determine whether the medium has finished being ejected by whether a predetermined time period has elapsed from when starting feed of the medium.

Next, the control module 151 stops the drive of the first motor 131 and the second motor 133 (step S116). The control module 151 controls the first motor 131 and the second motor 133 to make all of the rollers stop rotating and then ends the series of steps of the medium reading processing.

FIG. 7 is a flow chart showing an example of the operation of the medium ejection processing. Below, referring to the flow chart shown in FIG. 7 , an example of the operation of the medium ejection processing performed by the medium ejection apparatus 100 will be explained. Note that the flow of the operation explained below is mainly performed by the processing circuit 150 in concert with the elements of the medium ejection apparatus 100 based on a program stored in advance in the storage device 140. The medium ejection processing is performed each time one sheet of the medium is conveyed.

First, the control module 151 stands by until the back end of the medium passes the position of the third sensor 120 (step S201). The control module 151 determines whether the back end of the medium has passed the position of the third sensor 120 based on the third detection signal received from the third sensor 120.

If the back end of the medium has passed the position of the third sensor 120 (Yes at step S201), the control module 151 controls the first motor 131 so as to change the conveyance speed of the ejection roller 118 from the first conveyance speed to a second conveyance speed lower than the first conveyance speed (step S202). In other word, the control module 151 controls the drive mechanism 130 to control the conveyance speed of the ejection roller 118 when ejecting the medium.

In the above way, the third sensor 120 is located between the fifth conveyance roller 115 e located just before the ejection roller 118 and the ejection roller 118. The distance between the two rollers located adjoining each other is set so as to be larger than the smallest size of the medium which the medium ejection apparatus 100 supports. Therefore, if the back end of the medium has passed the position of the third sensor 120, the control module 151 determines that the medium is being ejected and changes the conveyance speed of the ejection roller 118 from the first conveyance speed to the second conveyance speed in the middle of ejecting the medium.

The higher the conveyance speed of the medium is, the shorter the time period required for conveying the medium is and the shorter the processing time of the medium reading processing by the medium ejection apparatus 100 is. However, according to the theory of projectile motion, the higher the conveyance speed of the medium is, the greater the amount by which the medium will spring out from the ejection roller 118 is. Therefore, the higher the conveyance speed of the medium is, the more the medium will end up scattered on the ejection tray 104 and the lower the alignment of the medium stacked on the ejection tray 104 is. Therefore, the user will have to align the medium stacked on the ejection tray 104 and the user will be inconvenienced. The medium ejection apparatus 100 conveys the medium by a high first conveyance speed until right before ejecting the medium while ejects the medium by a low second conveyance speed when ejecting the medium. Due to this, the medium ejection apparatus 100 can shorten the processing time of the medium reading processing while improving the alignment of the medium stacked on the ejection tray 104 and improving convenience to the user.

Further, the control module 151 changes the first conveyance speed to the second conveyance speed in accordance with detection of the medium by the third sensor 120. By using the third sensor 120, the control module 151 can determine with a high precision whether the medium, in particular the back end of the medium, is being ejected and can change the conveyance speed of the ejection roller 118 at a suitable timing.

As explained above, the distance between the third sensor 120 and the ejection roller 118 is set to larger than 2 mm and 5 mm or less in range. For this reason, the region of the medium conveyed at the second conveyance speed by the ejection roller 118 is the range of larger than 2 mm and 5 mm or less from the back end of the medium.

If the region of the medium conveyed at the second conveyance speed by the ejection roller 118 is 2 mm or less from the back end of the medium, the region of the medium conveyed at the second conveyance speed by the ejection roller 118 will be too small. For this reason, there is a possibility of the medium not being ejected at the second conveyance speed due to variations in roller diameter or sensor placement positions, etc. On the other hand, as a result of tests on conveying various types of medium while changing the position of change of the second conveyance speed, it was confirmed that if changing the second conveyance speed at a position 5 mm away from the back end of the medium, the probability of the front end of the following medium striking the back end of the preceding medium rapidly increases.

By the region of the medium conveyed at the second conveyance speed being set to larger than 2 mm and 5 mm or less in range, the medium ejection apparatus 100 can efficiently change the conveyance speed of the medium without regard as to variations in the parts, etc., of each apparatus while keeping collision with the consecutively conveyed medium from occurring. Therefore, the medium ejection apparatus 100 can keep the medium from jamming and keep the medium from being damaged.

Note that the timing for changing the conveyance speed of the ejection roller 118 from the first conveyance speed to the second conveyance speed may be another timing as well if in the middle of ejecting the medium. For example, the control module 151 may change the conveyance speed of the ejection roller 118 from the first conveyance speed to the second conveyance speed when the front end of the medium passes the position of the ejection roller 118. In this case, the control module 151 periodically receives the third detection signal from the third sensor 120 and determines the back end of the medium has passed the position of the third sensor 120 if the signal value of the third detection signal changes from a value showing there is no medium present to a value showing there is.

The control module 151 changes the second conveyance speed in accordance with the size of the medium detected by the size detection module 153. The control module 151 lowers the second conveyance speed as the size of the medium conveyed is smaller and raises the second conveyance speed as the size of the medium conveyed is larger. The smaller the size of the medium is, the smaller the weight of the medium is and the larger the amount by which the medium springs out from the ejection roller 118 is. For this reason, the smaller the size of the medium is, the higher the possibility of the medium ending up scattered on the ejection tray 104 and of the alignment of the medium stacked on the ejection tray 104 becoming lower is. On the other hand, if the size of the medium is large, there is a possibility of the front end of the medium contacting the stacking surface 104 a of the ejection tray 104 or the surface of the medium ejected right before, in advance of the back end of the medium being ejected. In this case, due to the friction between the medium being ejected and the stacking surface 104 a or the medium ejected right before, the medium being ejected is given a force heading toward the opposite side (upstream side) of the medium ejection direction A2. Due to this, if the conveyance speed of the ejection roller 118 is too low, there is a possibility of abnormal ejection (stack error) such as buckling of the back end of the medium occurring. Further, if the conveyance speed of the ejection roller 118 is too low, there is a possibility of abnormal ejection (stack error) occurring where the medium is not suitably stacked on the ejection tray 104 while the back end of the medium remains abutting against the ejection roller 118 or the wall formed at the upstream end of the ejection tray 104.

The medium ejection apparatus 100 lowers the second conveyance speed as the size of the medium conveyed is smaller. Due to this, the medium ejection apparatus 100 can align the back end positions of the medium on the ejection tray 104 even when a small sized medium is ejected and can improve the alignment of the medium stacked on the ejection tray 104. Further, the medium ejection apparatus 100 can prevent a small sized medium from being strongly pushed out and being placed at a downstream side position on the ejection tray 104 and the front end of the following medium from slipping beneath the back end of the preceding medium resulting in the sequence of the medium ending up being switched. Further, the medium ejection apparatus 100 raises the second conveyance speed as the size of the medium conveyed is larger. Due to this, the medium ejection apparatus 100 can suppress occurrence of abnormal ejection of the medium even if large sized medium is conveyed.

The control module 151, for example, makes the second conveyance speed in the case where the size of the medium is less than a threshold value lower than the second conveyance speed in the case where the size of the medium is the threshold value or more. The threshold value is, for example, set to the size of the medium (for example, A3 size) where the front end of the medium contacts the stacking surface 104 a of the ejection tray 104 when the back end of the medium passes the nip position of the ejection roller 118. Due to this, the medium ejection apparatus 100 can improve the alignment of a medium which easily is scattered while it can suppress occurrence of abnormal ejection of a medium in which abnormal ejection easily occurs.

In medium ejection apparatuses in recent years, higher conveyance speed of the medium is being demanded. As the first conveyance speed, 900 mm/sec or so in speed is set. On the other hand, as a result of tests conducted for conveying an A3 size medium while changing the conveyance speed, it was confirmed that if the conveyance speed is 230 mm/sec or less, the probability of occurrence of abnormal ejection of the medium rapidly rises. Further, in the tests, it was confirmed that if the conveyance speed is 300 mm/sec or more, the probability of occurrence of scattering of the medium rapidly rises. For this reason, the second conveyance speed of the medium in the case of a size of the medium of the threshold value or more is preferably set to larger than 230 mm/sec and smaller than 300 mm/sec in range.

Further, to improve the alignment of the medium, the second conveyance speed of a medium with a size of the medium of a threshold value or more is preferably made as slow as possible. On the other hand, tests were conducted for conveying various sizes of medium while changing the conveyance speed. As a result, it was confirmed that if the conveyance speed is 160 mm/sec or less, the probability of the front end of a following medium approaching or striking the back end of the preceding medium rapidly rises. For this reason, the second conveyance speed of the medium in the case of a size of the medium of the threshold value or less is preferably set to larger than 160 mm/sec and smaller than 300 mm/sec in range.

Therefore, the ratio of the first conveyance speed and the second conveyance speed, i.e., the ratio of the second conveyance speed to the first conveyance speed, is preferably set to 3.0 or more and 5.6 or less in range.

Note that the control module 151 may also change the second conveyance speed of the ejection roller 118 to multiple stages of three stages or more in accordance with the size of the medium conveyed.

Next, the control module 151 stands by until the back end of the medium passes the position of the ejection roller 118 (step S203). In the same way as the processing of step S115, the control module 151 determines whether the back end of the medium has passed the position of the ejection roller 118 by whether a third predetermined time period has passed after the back end of the medium passes the position of the third sensor 120.

If the back end of the medium has passed the position of the ejection roller 118 (Yes at step S203), the control module 151 controls the first motor 131 so as to again change the conveyance speed of the medium from the second conveyance speed to the first conveyance speed (step S204). Due to this, the following medium is conveyed by the ejection roller 118 by a high first conveyance speed, so the medium ejection apparatus 100 can shorten the processing time of the medium reading processing. Due to the above, the control module 151 ends the series of the medium ejection processing.

When the control module 151 changes the conveyance speed of the ejection roller 118 from the first conveyance speed to the second conveyance speed at step S202, it does not change the conveyance speed of the feed roller 113 or the first to fifth conveyance rollers 115 a to 115 e from the first conveyance speed. Due to this, the conveyance speed of the medium which follows the medium being ejected and which is being captured by the imaging devices 117 does not change. Therefore, the control module 151 can keep distortion of the medium caused by a change of the conveyance speed of the medium during image capture from occurring inside input images generated by the imaging devices 117.

Note that when the control module 151 changes the conveyance speed of the ejection roller 118 from the first conveyance speed to the second conveyance speed at step S202, it may also change the conveyance speed of the feed roller 113 or the first to fifth conveyance rollers 115 a to 115 e from the first conveyance speed to the second conveyance speed. In particular, the control module 151 changes the conveyance speed of the first to fifth conveyance rollers 115 a to 115 e to a speed the same as the conveyance speed of the ejection roller 118. Due to this, even if lowering the conveyance speed of the ejection roller 118, the distance between the back end of the medium being ejected and the front end of the following medium does not change. Therefore, the control module 151 can keep the back end of the medium being ejected and the front end of the following medium from colliding and jamming of the medium occurring.

Further, in this case, the feed roller 113 or the first to fifth conveyance rollers 115 a to 115 e may be provided so as to not rotate in accordance with the drive force from the second motor 133, but to rotate in accordance with the drive force from the first motor 131. Due to this, the medium ejection apparatus 100 can make the motor for driving several types of rollers the same and can be reduced in apparatus cost, apparatus size, and apparatus weight.

Further, at step S114 of FIG. 6 , the control module 151 may change the timing of resumption of feed of the medium in accordance with the size of the medium. The control module 151 delays the timing of resumption of feed of the medium as the size of the medium conveyed is smaller, i.e., as the second conveyance speed is lower, and accelerates the timing of resumption of feed of the medium as the size of the medium conveyed is larger, i.e., as the second conveyance speed is higher. Due to this, even if lowering the conveyance speed of the ejection roller 118, the distance between the back end of the medium being ejected and the front end of the following medium is suitably secured. Therefore, the control module 151 can keep the back end of the medium being ejected and the front end of the following medium from colliding and jamming of the medium occurring.

As explained above in detail, the medium ejection apparatus 100 performs brake ejection for reducing the conveyance speed of the medium in accordance with the size of the medium to improve the alignment of the medium at the ejection tray and prevent abnormal ejection of the medium. Therefore, the medium ejection apparatus 100 can efficiently eject several types of a medium having respectively different sizes to the ejection tray 104.

In general, if the stacking surface of the ejection tray is greatly inclined with respect to the horizontal plane, the medium ejected to the ejection tray will move due to its own weight thereby easily causing abnormal ejection of the medium. The medium ejection apparatus 100 reduces the conveyance speed of the ejection roller 118 at the time of medium ejection whereby even if the stacking surface 104 a of the ejection tray 104 is greatly inclined with respect to the horizontal plane, it can keep abnormal ejection of the medium from occurring. Therefore, the medium ejection apparatus 100 can be reduced in size (area of apparatus) seen from the height direction A3.

FIG. 8 is a view showing the schematic constitution of the processing circuit 250 of the medium ejection apparatus according to another embodiment.

As shown in FIG. 8 , the processing circuit 250 is used in place of the processing circuit 150 of the medium ejection apparatus 100 shown in FIG. 3 and FIG. 4 . The processing circuit 250 has a control circuit 251, image acquisition circuit 252, size detection circuit 253, etc. Note that these parts may also be constituted by respectively independent integrated circuits, microprocessors, firmware, etc.

The control circuit 251 is one example of the control module and has a function similar to the control module 151. The control circuit 251 receives operating signals from the operating device 105 or the interface device 134 and detection signals from the first sensor 111, the second sensor 119, and the third sensor 120. Further, the control circuit 251 receives the size of the medium from the size detection circuit 253. The control circuit 251 controls the first motor 131 and the second motor 133 based on the information received.

The image acquisition circuit 252 is one example of the image acquisition module and has a function similar to the image acquisition module 152. The image acquisition circuit 252 receives input images from the imaging devices 117 and stores the received input images in the storage device 140 or outputs them to the interface device 134.

The size detection circuit 253 is one example of the size detection module and has a function similar to the size detection module 153. The size detection circuit 253 detects the size of the medium based on the second detection signal received from the second sensor 119. The size detection circuit 253 sends the detected size of the medium to the control circuit 251.

The medium ejection apparatus, medium ejection method, and control program can efficiently eject several types of a medium having respectively different sizes to an ejection tray.

All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiment(s) of the present inventions have been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereto without departing from the spirit and scope of the invention. 

What is claimed is:
 1. A medium ejection apparatus comprising: an ejection roller; an ejection tray to stack a medium ejected by the ejection roller; a drive mechanism to drive the ejection roller; a processor to detect a size of the medium ejected by the ejection roller, and control the drive mechanism to control a conveyance speed of the ejection roller when ejecting the medium, wherein the processor changes the conveyance speed of the ejection roller from a first conveyance speed to a second conveyance speed lower than the first conveyance speed in the middle of ejecting the medium, and wherein the processor changes the second conveyance speed in accordance with the size of the medium.
 2. The medium ejection apparatus according to claim 1, wherein a ratio of the first conveyance speed and the second conveyance speed is 3.0 or more and 5.6 or less.
 3. The medium ejection apparatus according to claim 1, wherein a region of the medium conveyed at the second conveyance speed by the ejection roller is larger than 2 mm and 5 mm or less from a back end of the medium.
 4. The medium ejection apparatus according to claim 1, further comprising a medium detection sensor located at an upstream side from the ejection roller in the medium conveyance direction, and wherein the processor changes the first conveyance speed to the second conveyance speed in accordance with detection of the medium by the medium detection sensor.
 5. A medium ejection method comprising: detecting a size of a medium ejected by an ejection roller to eject the medium to an ejection tray; and controlling a drive mechanism to drive the ejection roller, to control a conveyance speed of the ejection roller when ejecting the medium, wherein the conveyance speed of the ejection roller is changed from a first conveyance speed to a second conveyance speed lower than the first conveyance speed in the middle of ejecting the medium, and wherein the second conveyance speed is changed in accordance with the size of the medium.
 6. The medium ejection method according to claim 5, wherein a ratio of the first conveyance speed and the second conveyance speed is 3.0 or more and 5.6 or less.
 7. The medium ejection method according to claim 5, wherein a region of the medium conveyed at the second conveyance speed by the ejection roller is larger than 2 mm and 5 mm or less from a back end of the medium.
 8. The medium ejection apparatus according to claim 5, wherein the first conveyance speed is changed to the second conveyance speed in accordance with detection of the medium by a medium detection sensor located at an upstream side from the ejection roller in the medium conveyance direction.
 9. A computer-readable, non-transitory medium storing a computer program, wherein the computer program causes a medium ejection apparatus including an ejection roller, an ejection tray to stack a medium ejected by the ejection roller, and a drive mechanism to drive the ejection roller to execute a process, the process comprising: detecting a size of a medium ejected by the ejection roller; and controlling the drive mechanism to control a conveyance speed of the ejection roller when ejecting the medium, wherein the conveyance speed of the ejection roller is changed from a first conveyance speed to a second conveyance speed lower than the first conveyance speed in the middle of ejecting the medium, and wherein the second conveyance speed is changed in accordance with the size of the medium.
 10. The computer-readable, non-transitory medium according to claim 9 wherein a ratio of the first conveyance speed and the second conveyance speed is 3.0 or more and 5.6 or less.
 11. The computer-readable, non-transitory medium according to claim 9 wherein a region of the medium conveyed at the second conveyance speed by the ejection roller is larger than 2 mm and 5 mm or less from a back end of the medium.
 12. The computer-readable, non-transitory medium according to claim 9 wherein the medium ejection apparatus further includes a medium detection sensor located at an upstream side from the ejection roller in the medium conveyance direction, and wherein the first conveyance speed is changed to the second conveyance speed in accordance with detection of the medium by the medium detection sensor. 